Leiomyomas are ovarian steroids-sensitive benign uterine tumors with fibrotic characteristics that occur more frequently in African Americans as compared to other ethnic groups. Transforming growth factor beta (TGF-[unreadable]) is a multifunction cytokine whose overexpression serves as a key regulator of tissue fibrosis. I have identified that TGF-[unreadable], TGF-[unreadable] receptors (TGF-[unreadable]R) and their signaling molecules, Smads, are over-expressed in leiomyoma and leiomyoma smooth muscle cells (LSMC) as compared to myometrium and MSMC. Recently microRNA (miRNA) has been identified to play a central role in gene expression stability through transcriptional regression and degradation. I have identified the expression of a number of miRNAs in paired myometrium and leiomyomas and their isolated smooth muscle cells (MSMC and LSMC), including miR-20a, miR-21, miR-26a and miR-181a, predicted to target the expression of many genes including TGF-[unreadable], TGF-[unreadable]Rs and Smads. The expression of these miRNAs is regulated by ovarian steroids and gain- and loss-of-function of miR-21 resulted in altered expression of TGF-[unreadable] type-IIR in LSMC. Based on these results I hypothesized that miRNAs targeting the expression of TGF-[unreadable], TGF-[unreadable]R and Smads in leiomyomas are expressed in menstrual cycle- and ethnic-dependent manners, regulated by ovarian steroids, and gain- and loss-of their functions alter the expression of TGF-[unreadable], thus influencing the outcome of multiple cellular activities critical to leiomyomas'fibrotic characteristic. To test this hypothesis I propose two specific aims. Aim #1 will assess the expression of miR-18a, 21, 181a, and their predicted target genes TGF-[unreadable], TGF-[unreadable]Rs and Smads in paired myometrium and leiomyoma throughout the menstrual cycle, based on ethnicity. Utilizing gene microarray profiles previously obtained for paired leiomyoma and myometrium, I will identify and determine the functional annotation of these miRNAs'overall target genes. Aim #2 will assess the regulatory function of ovarian steroids on the expression of these miRNAs and influence of their gain- and loss-of functions using 2'O-methyl-modified miRNA decoys on the expression of their predicted target genes, cell growth and apoptosis. To achieve these aims, I will utilize real-time PCR, Western blotting, transfection, cell growth and apoptotic assays. The information gained from these studies will lead to identification of a novel molecular mechanism directed by miRNAs resulting in regulation of TGF-[unreadable] system, including in leiomyoma and allows for development of novel therapeutic strategies to mange leiomyoma growth. PUBLIC HEALTH RELEVANCE: Fibroids are benign uterine tumors estimated to develop in 70% of women during their reproductive years, with symptomatic tumors causing chronic pelvic pain and abnormal uterine bleeding. This proposal will investigate how fibroids grow and ways to prevent their symptoms and growth.